It is common to use an air conditioning system comprising a plurality of indoor units that jointly air conditions the same space. There are air conditioning systems that adjust both the temperature and the humidity in a room. In such air conditioning systems, it is common that each indoor unit has both a temperature adjustment function and a humidity adjustment function, and each indoor unit simultaneously adjusts the temperature and the humidity in a room (refer to Japanese Published Patent Application No. H6-129692). For example, there are air conditioning systems wherein each indoor unit comprises a heat exchanger, an indoor fan, and a humidifier. The heat exchanger adjusts the temperature of the air sent to the room by exchanging heat with the air that passes therethrough. The indoor fan generates an airflow that passes through the heat exchanger and is sent to the room. The humidifier humidifies the air sent to the room. In this type of air conditioning system, the indoor fan generates the airflow, and the temperature of this airflow is adjusted by the indoor heat exchanger and is also humidified by the humidifier.
However, in an air conditioning system as described above, the situation arises wherein each indoor unit frequently operates principally to adjust the temperature, and the humidity is not appropriately adjusted. To raise an example of the above, although each indoor unit performs temperature adjustment as well as humidity adjustment, each indoor unit sometimes transitions to a thermo-off state to perform temperature adjustment. In the thermo-off state, the indoor fan is stopped, and humidified air is consequently no longer sent to the room. Consequently, the humidity in the room becomes insufficiently adjusted.